<template>
<div class="music-list">
  <div class="back" @click="back">
    <i class="icon-back"></i>
  </div>
  <h1 class="title" v-html="title"></h1>
  <div class="bg-image" :style="bgStyle" ref="bgImage">
    <div class="play-wrapper">
      <div class="play" v-show="songs.length>0" ref="playBtn" @click="random">
        <i class="icon-play"></i>
        <span class="text">随机播放全部</span>
      </div>
    </div>
    <div class="filter" ref="filter"></div>
  </div>
  <div class="bg-layer" ref="layer"></div>
  <scroll @scroll="scroll" :probe-type="probeType" :listen-scroll="listenScroll" :data="songs" class="list" ref="list">
    <div class="song-list-wrapper">
      <songList @select="selectItem" :songs="songs" :rank="rank"></songList>
    </div>
    <div class="loading-container" v-show="!songs.length">
      <loading></loading>
    </div>
  </scroll>
</div>
</template>

<script type="text/ecmascript-6">
import Scroll from 'base/scroll/scroll'
import SongList from 'base/song-list/song-list'
import {
  playlistMixin
} from 'common/js/mixin'
import {
  prefixStyle
} from 'common/js/dom'
import Loading from 'base/loading/loading'
import {
  mapActions
} from 'vuex'

const RESERVED_HEIGHT = 40
const transform = prefixStyle('transform')
const backdrop = prefixStyle('backdrop-filter')
export default {
  mixins: [playlistMixin],
  props: {
    bgImage: {
      type: String,
      default: ''
    },
    songs: {
      type: Array,
      default: []
    },
    title: {
      type: String,
      default: ''
    },
    rank: {
      type: Boolean,
      default: false
    }
  },
  computed: {
    bgStyle() {
      return `background-image:url(${this.bgImage})`
    }
  },
  data() {
    return {
      scrollY: 0
    }
  },
  created() {
    this.probeType = 3
    this.listenScroll = true
  },
  mounted() {
    this.imageHeight = this.$refs.bgImage.clientHeight
    this.minTranslateY = -this.imageHeight + RESERVED_HEIGHT
    this.$refs.list.$el.style.top = `${this.imageHeight}px`
  },
  methods: {
    handlePlaylist(playlist) {
      const bottom = playlist.length > 0 ? '60px' : ''
      this.$refs.list.$el.style.bottom = bottom
      this.$refs.list.refresh()
    },
    scroll(pos) {
      this.scrollY = pos.y
    },
    back() {
      this.$router.back()
    },
    selectItem(item, index) {
      this.selectPlay({
        list: this.songs,
        index: index
      })
    },
    random() {
      this.randomPlay({
        list: this.songs
      })
    },
    ...mapActions([
      'selectPlay',
      'randomPlay'
    ])
  },
  watch: {
    scrollY(newY) {
      let tranlateY = Math.max(this.minTranslateY, newY)
      let zIndex = 0
      let scale = 1
      let blur = 0
      this.$refs.layer.style[transform] = `translate3d(0,${tranlateY}px,0)`
      const percent = Math.abs(newY / this.imageHeight)
      if (newY > 0) {
        scale = 1 + percent
      } else {
        blur = Math.min(20 * percent, 20)
      }
      this.$refs.filter.style[backdrop] = `blur(${blur}px)`
      if (newY < this.minTranslateY) {
        zIndex = 10
        this.$refs.bgImage.style.paddingTop = 0
        this.$refs.bgImage.style.height = `${RESERVED_HEIGHT}px`
        this.$refs.playBtn.style.display = 'none'
      } else {
        this.$refs.bgImage.style.paddingTop = '70%'
        this.$refs.bgImage.style.height = 0
        this.$refs.playBtn.style.display = ''
      }
      this.$refs.bgImage.style.zIndex = zIndex
      this.$refs.bgImage.style[transform] = `scale(${scale})`
    }
  },
  components: {
    Scroll,
    SongList,
    Loading
  }
}
</script>
<style scoped lang="stylus" rel="stylesheet/stylus">
@import "~common/stylus/variable"
 @import "~common/stylus/mixin"

.music-list
   position: fixed
   z-index: 100
   top: 0
   left: 0
   bottom: 0
   right: 0
   background: $color-background
   .back
     position absolute
     top: 0
     left: 6px
     z-index: 50
     .icon-back
       display: block
       padding: 10px
       font-size: $font-size-large-x
       color: $color-theme
   .title
     position: absolute
     top: 0
     left: 10%
     z-index: 40
     width: 80%
     no-wrap()
     text-align: center
     line-height: 40px
     font-size: $font-size-large
     color: $color-text
   .bg-image
     position: relative
     width: 100%
     height: 0
     padding-top: 70%
     transform-origin: top
     background-size: cover
     .play-wrapper
       position: absolute
       bottom: 20px
       z-index: 50
       width: 100%
       .play
         box-sizing: border-box
         width: 135px
         padding: 7px 0
         margin: 0 auto
         text-align: center
         border: 1px solid $color-theme
         color: $color-theme
         border-radius: 100px
         font-size: 0
         .icon-play
           display: inline-block
           vertical-align: middle
           margin-right: 6px
           font-size: $font-size-medium-x
         .text
           display: inline-block
           vertical-align: middle
           font-size: $font-size-small
     .filter
       position: absolute
       top: 0
       left: 0
       width: 100%
       height: 100%
       background: rgba(7, 17, 27, 0.4)
   .bg-layer
     position: relative
     height: 100%
     background: $color-background
   .list
     position: fixed
     top: 0
     bottom: 0
     width: 100%
     background: $color-background
     .song-list-wrapper
       padding: 20px 30px
     .loading-container
       position: absolute
       width: 100%
       top: 50%
       transform: translateY(-50%)

</style>
